Bacteria are capable of producing thin, transparent plastic films (polylactic acid (PLA)) and plastics commonly used for medical applications (poly-3-hydroxybutyrate (PHB)). However, unlike some other bioplastics, coaxing bacteria to make PLA or PHB has traditional required feeding them a diet of sugar (glucose). Thus this class of non-fossil fuel based plastics raises similar food crop issues to corn ethanol.

But Victor Irorere, a Masters student in biotechnology at the University of Warwick in the United Kingdom, has offered an alternative, showing that the bacteria can be coaxed to process waste oil (think french fries) instead of the traditional glucose carbon source.

Comments Mr. Irorere, "Our bioplastic-producing bacterium, Ralstonia eutropha H16, grew much better in oil over 48 hours and consequently produced three times more PHB than when it was grown in glucose. Electrospinning experiments, performed in collaboration with researchers from the University of Birmingham, showed that nanofibres of the plastic produced from oils were also less crystalline, which means the plastic is more suited to medical applications."

PLA and PLB are considered promising alternatives to petroleum plastics if costs can be reduced. One advantage -- aside from improved biocompatibility -- is that the bioplastics are biodegradable, reducing landfill waste.

PLA makes thin films that can be used as plastic wrap or in bags (right).
[Image Source: Google Images]

The study's senior author was Iza Radecka, a senior lecturer in microbiology at U of W. She comments, "The use of biodegradable plastics such as PHB is encouraged to help reduce environmental contamination. Unfortunately the cost of glucose as a starting material has seriously hampered the commercialization of bioplastics. Using waste cooking oil is a double benefit for the environment as it enables the production of bioplastics but also reduces environmental contamination caused by disposal of waste oil."

Following a presentation at the Society for General Microbiology's Autumn Conference, the researchers hope to expand their work to commercial-scale tests.

the possibility of mutated forms of these bacteria that hunger after lipids, say the oil on yr face? i'll admit to vast ignorance about this sort of thing. but one does wonder, after all, how much we understand about such processes and their permutations. i in no way mean to imply that we shouldn't play around w/ genetic manipulation, etc., only that we give ourselves time and space in which to fully explore the consequences. some primal peoples would deeply consider the impact current decisions and actions might have on future generations, a tack we would do well to emulate. just saying...

quote: the possibility of mutated forms of these bacteria that hunger after lipids, say the oil on yr face?

They already exist. You're covered with and also full of bacteria. You are a walking, talking, breathing, farting, pooping, pissing ecosystem.

It's not just a matter of "bacteria eats oil". That's fairly common. This story is a matter of "bacteria eats oil AND produces something useful because of it".

quote: some primal peoples would deeply consider the impact current decisions and actions might have on future generations, a tack we would do well to emulate.

Caution is indeed good advice, but the other side of the coin is that there is a point - usually arbitrary - where we need to accept that further knowledge is not likely to benefit us much. We can keep extracting information from almost anything, in perpetuity; the problem is "diminishing returns".

yes, i know about and understand we're all inundated, through-and-through w/ bacteria. even "our" mitochondria are borrowed (stipulated to be, at one time, a completely separate organism living symbiotically w/ other organisms...), now an integral/essential part of cell metabolism.

and i'm in no way insensate to the purpose and use these new forms of bacteria are being put to. commendable. and hey, i read this article because i'm utterly fascinated by science in all it's manifestations (read quite a bit in the field, actually, esp. medical science).

i agree, there is always another side of the coin. my intent here was/is to point out the side of the coin that often goes ignored. a sort of blind trust that the products of science/technology are good or will somehow save us is rampant (lots has been written on this, of course)--though these attitudes are changing as more and more of us wake up to the reality of, for instance, global warming (that's of course, not merely an issue of technology, but one of sociology as well; e.g., too many of us).

diminishing returns. interesting concept. one aspect of this notion arises, i think, from a mindset that fails to see at the outset inherent limitations of any given system (not meaning to intimate, hint or implicate you in this--simply riffing on the concept in general). if one starts from a perspective that views all systems as fundamentally limited, ipso facto, then the concept of diminishing returns sorta fades, ceases to matter. how can we begin to believe or perceive that we are getting less from a given input of energy if, from the outset, we operate from w/in the recognition of a given system's inherent limitations? conversely, diminishing returns only appears to happen when, from the outset, we operate from a perspective that the system is unlimited--the notion of perpetual growth. one only need look at our current economic systems to see this notion at work: it's all about perpetual growth and it's completely unsustainable.

quote: a sort of blind trust that the products of science/technology are good or will somehow save us is rampant

Uh, no, I don't think so. Our culture is rife with tales of the danger of playing with forces we don't understand. You ever hear of "Frankenstein"?

quote: how can we begin to believe or perceive that we are getting less from a given input of energy if, from the outset, we operate from w/in the recognition of a given system's inherent limitations?

Uh.... huh?

You're asking how we can perceive in a system's inherent limitations if we automatically assume a system has inherent limitations?

quote: conversely, diminishing returns only appears to happen when, from the outset, we operate from a perspective that the system is unlimited

Now I'm really lost. "Perspective" doesn't matter. Diminishing returns happen no matter what our perspective is. It's an essentially arbitrary dividing line where one accepts that the efforts required to continue developing data are no longer worth the potential gain. Perspective plays a role in deciding where the cut-off will be, but the diminishing returns are there regardless.

quote: coaxing bacteria to make PLA or PHB has traditional required feeding them a diet of sugar (glucose). Thus this class of non-fossil fuel based plastics raises similar food crop issues to corn ethanol.

I've espoused before the problems with corn ethanol (it's only financially viable because the U.S. subsidizes corn to deliberately overproduce). But people on the anti-corn ethanol bandwagon have taken it too far and started to automatically apply it to any crop-based ethanol.

Plants make sugars via photosynthesis. They take the energy from sunlight, and store it in a string of carbon-hydrogen-oxygen molecules we know as sugars. The primary one is glucose.

Carbohydrates are starches - basically multiple glucose molecules glued together. So essentially carbs are sugars glued together to make a large molecule. Your body uses sucrose and carbs as fuel by splitting them, freeing the basic glucose and fructose.

Notice a pattern? Basically a (C1 H2 O1)n arrangement, give or take one or two H or O.

Cellulose is (C6 H10 O5)n. It's a sugar! Plants take the glucose they form via photosynthesis, and glue it together in different ways. Sometimes they glue it as starches to form meaty parts like potatoes. Sometimes they glue it as cellulose to form wood. (Only the outside of a tree, the part just under the bark, is alive. The wood core is just a sugar reservoir.) That's why wood burns so readily - it contains lots of solar energy locked up in the form of sugar molecules, combined to form wood.

To access the sugar in cellulose just involves breaking it down into its constituent sugars again. Most animals lack the enzymes to do this. Ruminants (most herbivores) get around this by doing a lot of chewing and having four stomachs to physically and chemically break the cellulose down to smaller molecular chains. They and termites then have bacteria which break down the cellulose into shorter sugar chains, which they can then use as food.

So just because the process for making ethanol (aka fermentation) requires sugar does not mean it needs a sugar crop. Certainly it's easier if the plant just stores the energy as plain sugars (sugar cane, sugar beets). But nature has ways to convert raw cellulose back into sugars. We just need to figure out a cost-effective and scalable way to do it. Once we do, all the excess plant matter we currently burn or throw away - wood, parts of plants we don't eat like corn stalks and husks, gardening and landscaping trimmings, even old furniture - can be converted into alcohol for fuel.

We *do* eat corn stalks and husks. After they've been fed to pigs, or plowed back under to fertilize the next crop of corn.

And it doesn't matter greatly whether your ethanol process requires a "food" crop or not...if tillable soil was used to grow a crop for any purpose other than food, then the food cycle is negatively impacted...period.

As for people who go off and say stupid things like "well [x] can be grown in soil that isn't tillable anyway, so nyah Xp !" - well, there's a reason that soil isn't tillable. And if we can't till it, we probably can't cultivate it. So exactly what good does it do to identify a plant that we can neither plant nor cultivate?